1. Field of the Invention
The present invention relates to an internal-surface-scanning image recording apparatus for efficiently recording an image on a recording medium.
2. Description of the Related Art
One type of image recording apparatus for recording an image on a sheet-like recording medium with a laser beam is known as an internal-surface-scanning image recording apparatus. The internal-surface-scanning image recording apparatus has a hollow cylindrical drum with a sheet-like recording medium attached to an inner circumferential surface thereof, and an optical system disposed coaxially in the drum for guiding a laser beam to the recording medium.
Specifically, as shown in FIG. 11 of the accompanying drawings, a spinner 4 disposed coaxially in a hollow cylindrical drum 6 has a reflecting surface inclined at 45.degree. to the optical axis of a laser beam L which is emitted from a laser beam source 2 positioned outside of the drum 6. When the spinner 4 is rotated about its own axis at a high speed and axially displaced along the central axis of the drum 6, the reflecting surface of the spinner 4 reflects the laser beam L to a recording medium F attached to an inner circumferential surface of the drum 6 to record a two-dimensional image on the recording medium F.
Since the recording medium F is attached to the inner circumferential surface of the drum 6, the recording medium F is prevented from being accidentally peeled off the drum 6 while the image is being recorded on the recording medium F, and the image can be recorded on the recording medium F with high dimensional accuracy.
The drum 6 has a slot 8 defined partly therein for allowing the recording medium F to be attached therethrough to the inner circumferential surface of the drum 6. Since no image is recorded while the laser beam L reflected by the reflecting surface of the spinner 4 traverses the slot 8, the internal-surface-scanning image recording apparatus shown in FIG. 11 suffers a waste of time and laser beam energy while in operation. As a result, the internal-surface-scanning image recording apparatus shown in FIG. 11 records an image on the recording medium F with relatively low efficiency.